package com.sfy.core.example.registry;

import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.collection.ConcurrentHashSet;
import cn.hutool.cron.CronUtil;
import cn.hutool.cron.task.Task;
import cn.hutool.json.JSONUtil;
import com.sfy.core.example.config.RegistryConfig;
import com.sfy.core.example.model.ServiceMetaInfo;
import io.etcd.jetcd.*;
import io.etcd.jetcd.options.GetOption;
import io.etcd.jetcd.options.PutOption;
import io.etcd.jetcd.watch.WatchEvent;
import lombok.extern.slf4j.Slf4j;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
@Slf4j
public class EtcdRegistry implements Registry {

    private Client client;

    private KV kvClient;

    /**
     * 根节点
     */
    private static final String ETCD_ROOT_PATH = "/rpc/";

    /**
     * 本机注册的节点key集合（用于维护续期）
     */
    private final Set<String> loaclRegistryNodeKeySet = new HashSet<>();

    /**
     * 注册中心缓存
     */
    private final RegistryServiceCache registryServiceCache = new RegistryServiceCache();

    /**
     * 正在监听key的集合
     */
    private final Set<String> watchKeySet = new ConcurrentHashSet<>();

    @Override
    public void init(RegistryConfig registryConfig) {
        client = Client.builder().endpoints(registryConfig.getAddress())
                .connectTimeout(Duration.ofMillis(registryConfig.getTimeout())).build();
        kvClient = client.getKVClient();
        heartBeat();
    }

    @Override
    public void register(ServiceMetaInfo serviceMetaInfo) throws Exception {
        // 创建 Lease 和 KV 客户端
        Lease leaseClient = client.getLeaseClient();

        // 创建一个 30 秒的租约
        long leaseId = leaseClient.grant(30).get().getID();

        // 设置要存储的键值对
        String registerKey = ETCD_ROOT_PATH + serviceMetaInfo.getServiceNodeKey();
        ByteSequence key = ByteSequence.from(registerKey, StandardCharsets.UTF_8);
        ByteSequence value = ByteSequence.from(JSONUtil.toJsonStr(serviceMetaInfo), StandardCharsets.UTF_8);

        // 将键值对与租约关联起来，并设置过期时间
        PutOption putOption = PutOption.builder().withLeaseId(leaseId).build();
        kvClient.put(key, value, putOption).get();

        /**
         * 添加节点信息到本地缓存
         */
        loaclRegistryNodeKeySet.add(registerKey);
    }

    @Override
    public void unRegister(ServiceMetaInfo serviceMetaInfo) {
        String registerKey = ETCD_ROOT_PATH + serviceMetaInfo.getServiceNodeKey();
        kvClient.delete(ByteSequence.from(registerKey, StandardCharsets.UTF_8));
        // 也要从本地缓存移除
        loaclRegistryNodeKeySet.remove(registerKey);
    }

    @Override
    public List<ServiceMetaInfo> serviceDiscovery(String serviceKey) {
        // 优先从缓存获取服务
        List<ServiceMetaInfo> cachedServiceMetaInfoList = registryServiceCache.readCache();
        if (cachedServiceMetaInfoList != null) {
            return cachedServiceMetaInfoList;
        }

        // 前缀搜索，结尾一定要加 '/'
        String searchPrefix = ETCD_ROOT_PATH + serviceKey + "/";
        log.info("searchPrefix的值为{}", searchPrefix);
        try {
            // 前缀查询
            GetOption getOption = GetOption.builder().isPrefix(true).build();
            List<KeyValue> keyValues = kvClient.get(
                            ByteSequence.from(searchPrefix, StandardCharsets.UTF_8),
                            getOption)
                    .get()
                    .getKvs();
            // 解析服务信息
            List<ServiceMetaInfo> serviceMetaInfoList = keyValues.stream()
                    .map(keyValue -> {
                        String key = keyValue.getKey().toString(StandardCharsets.UTF_8);
                        // 监听 key 的变化
                        watch(key);
                        String value = keyValue.getValue().toString(StandardCharsets.UTF_8);
                        return JSONUtil.toBean(value, ServiceMetaInfo.class);
                    })
                    .collect(Collectors.toList());
            // 写入服务缓存
            registryServiceCache.writeCache(serviceMetaInfoList);
            return serviceMetaInfoList;
        } catch (Exception e) {
            log.info("服务获取失败的原因是:{}", e.getMessage());
            throw new RuntimeException("获取服务列表失败", e);
        }
    }

    @Override
    public void destroy() {
        System.out.println("当前节点下线");
        // 下线节点，遍历所有的key
        for(String key: loaclRegistryNodeKeySet) {
            try{
                kvClient.delete(ByteSequence.from(key, StandardCharsets.UTF_8));
            }catch (Exception e){
                throw new RuntimeException(key+"下线失败");
            }

        }
        // 释放资源
        if (kvClient != null) {
            kvClient.close();
        }
        if (client != null) {
            client.close();
        }
    }

    @Override
    public void heartBeat() {
        //每十秒续签一次
        CronUtil.schedule("*/10 * * * * *", new Task(){
            @Override
            public void execute() {
                // 遍历本节点所有的key
                for(String key : loaclRegistryNodeKeySet) {
                    try{
                        List<KeyValue> keyValues = kvClient.get(ByteSequence.from(key, StandardCharsets.UTF_8))
                                .get().getKvs();
                        // 如果节点过期，需要重启节点才能注册
                        if(CollUtil.isEmpty(keyValues)){
                            continue;
                        }
                        // 节点为过期，重新注册
                        KeyValue keyValue = keyValues.get(0);
                        String value = keyValue.getValue().toString(StandardCharsets.UTF_8);
                        ServiceMetaInfo serviceMetaInfo = JSONUtil.toBean(value, ServiceMetaInfo.class);
                        register(serviceMetaInfo);
                    }catch (Exception e){
                        throw new RuntimeException(key+"续签失败",e);
                    }
                }
            }
        });
        CronUtil.setMatchSecond(true);
        CronUtil.start();
    }

    /**
     * 只监听首次加入到监听集合中的key，防止重复
     * @param serviceNodeKey
     */
    @Override
    public void watch(String serviceNodeKey) {
        Watch watchClient = client.getWatchClient();
        // 开启监听
        boolean newWatch = watchKeySet.add(serviceNodeKey);
        if (newWatch) {
            watchClient.watch(ByteSequence.from(serviceNodeKey,StandardCharsets.UTF_8),response->{
                for(WatchEvent event : response.getEvents()){
                    switch (event.getEventType()){
                        // key 删除时触发
                        case DELETE:
                            // 清除缓存
                            registryServiceCache.clearCache();
                            break;
                        case PUT:
                        default:
                            break;
                    }
                }
            });
        }
    }
}
